The overall objective of the proposed research is the characterization of the kinetics of growth and dissolution of synthetic renal stone-forming minerals such as calcium oxalate, uric acid, the urates, calcium phosphate and magnesium ammonium phosphate in supersaturated solutions and in synthetic urine. The highly reproducible procedure of seeded growth in stable supersaturated solutions, developed in our laboratory, will be used and a range of ionic strength, concentration and pH typical of those in urines will be studied in order to provide information about the nature of the solid phases formed in the stone-forming process. Emphasis will be placed on the elucidation of the factors controlling the formation of the mixed mineral solid phases (e.g., by epitaxy) found in renal stones; the influence of individual urine components on this process will be investigated. In parallel with these studies, specific surface area, scanning electronmicroscopic and electron microprobe investigations of the growing crystals will be made in order to relate crystal morphology to the kinetics of the growth process. The effects of potential stone inhibitors upon the mineralization and demineralizaton reactions will be studied using the same highly reproducible kinetic techniques and the extent of their adsorption at the mineral/solution interface will also be measured in order to relate the uptake to the measured rate of stone mineral formation. Dissolution kinetic studies will be made on the grown solids and on native renal stones in order to determine the nature of the solid phases formed in the mineralization experiments. Studies will also be made of the nucleation and growth of stone minerals on the organic matrix of renal stones. The information obtained from this proposed study will be helpful in the elucidation of the mechanism of renal stone formation and in the search for new and improved stone inhibitors capable of oral administration in the treatment of urolithiasis.